Wyverns

Wyverns are exceptionally large predatory birds, up to 4 m in height with a wingspan in excess of 9 m. They have a wide distribution, but because of the large amount of food such a large animal demands, they are very rare.   The wyvern has retained some retilian features, including wing claws; a long, bony tail; and teeth along the rim of the beak. However, the wyvern loses its teeth as it matures. It's believed that as a juvenile, the teeth allow the wyvern to finish tearing regurgitated flesh they aren't yet large enough to swallow.   There are at least three known varieties of the wyvern. The land wyvern is the most numerous; it typically makes its roost in mountain or cliff caves, where it can use a long drop to build speed to be able to fly or glide. While a wyvern is capable of taking off from the ground, doing so requires an enormous amount of energy, so naturally they prefer to avoid it if possible. The land wyvern's diet varies, depending on whether it is supporting a chick. If so, they prefer medium-large animals such as deer, sheep, or pigs (understandably, they are a nuisance for farmers), as they are able to carry the animal in their beak, claws, or stomach as they return to their roost. If not, the wyvern may go after larger prey, up to and including horses or oxen. Because so few animals are able to threaten the wyvern, they can simply linger over their kill, eating it at their leisure.   The sea wyvern roosts on water-facing bluffs. Unlike the land wyvern, it is principally nocturnal, allowing it to take advantage of land breezes carrying it out to the water to hunt and sea breezes to bring it home. And while the land wyvern tends to fly very high above its prey, the sea wyvern flies lower, allowing it to spot prey near the surface, typically large fish (such as tuna) or even aquatic mammals (such as dolphins). Despite its name, the sea wyvern may potentially be found near any body of water large enough to support this type of life. Sea wyverns are capable of supporting themselves on the water's surface and paddling with their feet, but this is extremely rare to see.   Both the land wyvern and sea wyvern have fairly similar hunting styles: they swoop down from a great height and strike with crushing force. And while both are capable of flying great distances and at great speed in short bursts, neither are particularly graceful at doing so. The third variety of wyvern, the domesticated or "house" wyvern, is a bit smaller than the wild varieties, with much sharper wings. Standing 3 m tall with a 6-7 m wingspan, house wyverns were cultivated millennia ago with the intention of creating a flying mount. While this was somewhat successful (though understandably dangerous for the first generations of riders), they lacked the endurance of horses, and feeding them was much more difficult. So, breeders began working towards their strengths, and over time the wyvern became smaller and better adapted to agile, short-range flight. While they remain extremely rare (and many still regard them as novelties or even white elephants), they have found many niche uses in modern human society.